AMPK Associates with Chromatin and Phosphorylates the TAF-1 Subunit of the Transcription Initiation Complex to Regulate Histone Gene Expression in ALL Cells.

The survival rates for relapsed/refractory acute lymphoblastic leukemia (ALL) remain poor. We and others have reported that ALL cells are vulnerable to conditions inducing energy/ER-stress mediated by AMP-activated protein kinase (AMPK). To identify the target genes directly regulated by AMPKα2, we performed genome-wide RNA-seq and ChIP-seq in CCRF-CEM (T-ALL) cells expressing HA-AMPKα2 (CN2) under normal and energy/metabolic stress conditions. CN2 cells show significantly altered AMPKα2 genomic binding and transcriptomic profile under metabolic stress conditions, including reduced histone gene expression. Proteomic analysis and in vitro kinase assays identified the TATA-Box-Binding Protein-Associated Factor 1 (TAF1) as a novel AMPKα2 substrate that downregulates histone gene transcription in response to energy/metabolic stress. Knockdown and knockout studies demonstrated that both AMPKα2 and TAF1 are required for histone gene expression. Mechanistically, upon activation, AMPKα2 phosphorylates TAF1 at Ser-1353 which impairs TAF1 interaction with RNA polymerase II (Pol II), leading to a compromised state of p-AMPKα2/p-TAF1/Pol II chromatin association and suppression of transcription. This mechanism was also observed in primary ALL cells and in vivo in NSG mice. Consequently, we uncovered a non-canonical function of AMPK that phosphorylates TAF1, both members of a putative chromatin-associated transcription complex that regulate histone gene expression, among others, in response to energy/metabolic stress. IMPLICATIONS: Fully delineating the protein interactome by which AMPK regulates adaptive survival responses to energy/metabolic stress, either via epigenetic gene regulation or other mechanisms, will allow the rational development of strategies to overcome de novo or acquired resistance in ALL and other cancers.

Energy differences as descriptors for the correlation between JSC and VOC in nonfullerene organic photovoltaics.

ITIC-series nonfullerene organic photovoltaics (NF OPVs) have realized the simultaneous increases of the short-circuit current density (JSC) and open-circuit voltage (VOC), called the positive correlation between JSC and VOC, which could improve the power conversion efficiency (PCE). However, it is complicated to predict the formation of positive correlation in devices through simple calculations of single molecules due to their dimensional differences. Here, a series of symmetrical NF acceptors blended with the PBDB-T donor were chosen to establish an association framework between the molecular modification strategy and positive correlation. It can be found that the positive correlation is modification site-dependent following the energy variation at the different levels. Furthermore, to illustrate a positive correlation, the energy gap differences (ΔEg) and the energy level differences of the lowest unoccupied molecular orbitals (ΔELUMO) between the two changed acceptors were proposed as two molecular descriptors. Combined with the machine learning model, the accuracy of the proposed descriptor is more than 70% for predicting the correlation, which verifies the reliability of the prediction model. This work establishes the relative relationship between two molecular descriptors with different molecular modification sites and realizes the prediction of the trend of efficiency. Therefore, future research should focus on the simultaneous enhancement of photovoltaic parameters for high-performance NF OPVs.

Effects of Multi-Walled Carbon Nanotubes and Nano-Silica on Root Development, Leaf Photosynthesis, Active Oxygen and Nitrogen Metabolism in Maize.

Carbon nanotubes (MWCNTs) and nano-silica (nano-SiO2) are widely used in the field of life science because of their special physical and chemical properties. In this study, the effects of different concentrations of MWCNTs (0 mg·L-1, 200 mg·L-1, 400 mg·L-1, 800 mg·L-1 and 1200 mg·L-1) and nano-SiO2 (0 mg·L-1, 150 mg·L-1, 800 mg·L-1, 1500 mg·L-1 and 2500 mg·L-1) on maize seedling growth and relative mechanisms were explored. The main results are as follows: MWCNTs and nano-SiO2 can promote the growth of maize seedlings, and promote plant height, root length, the dry and fresh weight of seedlings, root-shoot ratio and so on. The ability to accumulate dry matter increased, the relative water content of leaves increased, the electrical conductivity of leaves decreased, the stability of cell membranes improved and the water metabolism ability of maize seedlings increased. The treatment of MWCNTs with 800 mg·L-1 and nano-SiO2 with 1500 mg·L-1 had the best effect on seedling growth. MWCNTs and nano-SiO2 can promote the development of root morphology, increase root length, root surface area, average diameter, root volume and total root tip number and improve root activity, so as to improve the absorption capacity of roots to water and nutrition. After MWCNT and nano-SiO2 treatment, compared with the control, the contents of O2·- and H2O2 decreased, and the damage of reactive oxygen free radicals to cells decreased. MWCNTs and nano-SiO2 can promote the clearance of reactive oxygen species and maintain the complete structure of cells, so as to slow down plant aging. The promoting effect of MWCNTs treated with 800 mg·L-1 and nano-SiO2 treated with 1500 mg·L-1 had the best effect. After treatment with MWCNTs and nano-SiO2, the activities of key photosynthesis enzymes PEPC, Rubisco, NADP-ME, NADP-MDH and PPDK of maize seedlings increased, which promoted the opening of stomata, improved the fixation efficiency of CO2, improved the photosynthetic process of maize plants and promoted plant growth. The promoting effect was the best when the concentration of MWCNTs was 800 mg·L-1 and the concentration of nano-SiO2 was 1500 mg·L-1. MWCNTs and nano-SiO2 can increase the activities of the enzymes GS, GOGAT, GAD and GDH related to nitrogen metabolism in maize leaves and roots, and can increase the content of pyruvate, so as to promote the synthesis of carbohydrates and the utilization of nitrogen and promote plant growth.

Exogenous Hemin alleviates cadmium stress in maize by enhancing sucrose and nitrogen metabolism and regulating endogenous hormones.

Cadmium (Cd) stress restricts maize growth and productivity severely. We aimed to investigate the effects of Hemin on the metabolism of sucrose and nitrogen and endogenous hormones in maize under cadmium stress. Maize varieties 'Tiannong 9' (cadmium tolerant) and 'Fenghe 6' (cadmium sensitive) were grown in nutrient solutions to study the effects of Hemin on maize physiological and ecological mechanisms under cadmium stress. The results showed that Hemin mediated the increase of sucrose content and the activities of key enzymes sucrose phosphate synthase (SPS) and sucrose synthase (SS) in maize leaves under cadmium stress. Soluble acid invertase (SAInv) and basic/neutral invertase (A/N-Inv) enzyme activities in leaves were decreased significantly, and sucrose accumulation in leaves was increased. Hemin also mediated the increase of NO3- content in leaves, the decrease of NH4+ content and the increase of nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase activity (GOGAT) and glutamate dehydrogenase (GDH) enzyme activities under cadmium stress. The contents of IAA, ZR, and GA in leaves and roots increased, ABA, MeJA, and SA decreased, and IAA/ABA, ZR/ABA, and GA/ABA increased under cadmium stress. Our study showed Hemin can alleviate cadmium stress in maize by enhancing sucrose and nitrogen metabolism and regulating endogenous hormones.

This work further investigates the effects of Hemin on the metabolism of sucrose and nitrogen and endogenous hormones in maize under cadmium stress, which, hopefully, is to guide Hemin application to maize field resilience production. It also explains that Hemin is beneficial for dry matter accumulation and transport, alleviated ammonia toxicity and nitrogen metabolism disorder, and induced the changes of endogenous hormone content and the adaptive hormone ratio balance under cadmium stress.

Optimal Dihedral Angle in Twisted Donor-Acceptor Organic Emitters for Maximized Thermally Activated Delayed Fluorescence.

The twisted donor-acceptor (D-A) organic formwork with a large dihedral angle (θDA ) is usually adopted to narrow the singlet-triplet energy gap for obtaining excellent thermally activated delayed fluorescence (TADF) emitters. However, the dependence of overall TADF properties on θDA has not been systematically investigated to this day. Taking new designed CzBP, CzBP-1M and CzBP-2M via introducing methyl as investigated models, it is found that (i) with increasing θDA , the charge transfer component in S1 is larger than that in T1 in varying degrees, leading to non-monotonic spin-orbit couplings; (ii) the electron-vibration couplings between S1 and T1 states become the largest when θDA approaching 80°, facilitating phonon-driven up-conversion; (iii) the overall TADF rate reaches a peak at θDA ≈80°. By this, the TADF on/off switching is realized via methyl moiety for regulating θDA from theoretical prediction to experimental confirmation. Importantly, the θDA near 80° would be a good descriptor for screening excellent D-A type TADF emitters.

Exogenous Hemin alleviated cadmium stress in maize (Zea mays L.) by enhancing leaf photosynthesis, AsA-GSH cycle and polyamine metabolism.

Cadmium (Cd) stress is one of the principal abiotic stresses that inhibit maize growth. The research was to explore (hemin chloride) Hemin (100 µmol L-1) on photosynthesis, ascorbic acid (AsA)-glutathione (GSH) cycle system, and polyamine metabolism of maize under Cd stress (85 mg L-1) using nutrient solution hydroponics, with Tiannong 9 (Cd tolerant) and Fenghe 6 (Cd sensitive) as experimental materials. The results showed that Hemin can increase leaf photosynthetic pigment content and ameliorate the ratio of Chlorophyll a/chlorophyll b (Chla/Chlb) under Cd stress. The values of ribose 1, 5-diphosphate carboxylase/oxygenase (RuBPcase) and phosphoenolpyruvate carboxylase (PEPCase), and total xanthophyll cycle pool [(violoxanthin (V), antiflavin (A) and zeaxanthin (Z)] increased, which enhancing xanthophyll cycle (DEPS) de-epoxidation, and alleviating stomatal and non-stomatal limitation of leaf photosynthesis. Hemin significantly increased net photosynthetic rate (Pn ), stomatal conductance (gs ), transpiration rate (Tr ), photochemical quenching coefficient (qP), PSII maximum photochemical efficiency (Fv/Fm ), and electron transfer rate (ETR), which contributed to the improvement of the PSII photosynthetic system. Compared with Cd stress, Hemin can reduce thiobartolic acid reactant (TBARS) content, superoxide anion radical (O2 -) production rate, hydrogen peroxide (H2O2) accumulation, and the extent of electrolyte leakage (EL); decreased the level of malondialdehyde (MDA) content and increased the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT); slowed the decrease in dehydroascorbic acid reductase (DHAR) and monodehydroascorbate reductase (MDHAR) activity and the increase in glutathione reductase (GR) and ascorbate peroxidase (APX) activity in leaves; promoted the increase in AsA and GSH content, decreased dehydroascorbic acid (DHA) and oxidized glutathione (GSSG), and increased AsA/DHA and GSH/GSSG ratios under Cd stress. Hemin promoted the increase of conjugated and bound polyamine content, and the conversion process speed of free putrescine (Put) to free spermine (Spm) and spermidine (Spd) in maize; decreased polyamine oxidase (PAO) activity and increased diamine oxidase (DAO), arginine decarboxylase (ADC), ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) enzyme activities in leaves under Cd stress.

The effect of heavy atoms replacement sites on the luminescent ways of D-A-D type diphenyl sulfone molecules: Thermally activated delayed fluorescence and phosphorescence.

To obtain efficient pure organic thermally activated delayed fluorescence (TADF) materials, introducing non-metal heavy atoms is the common molecular design strategy, enhancing the intrinsically weak spin-orbit coupling (SOC) between singlet and triplet excited states by heavy-atom effect. However, the effect of heavy atom replacement sites is rarely explored. Herein, two series of molecules are investigated on the basis of different heavy atoms replacement sites to reveal the inherent structure-property relationships. The results show that DMSeC-DPS, which O is replaced with Se in periphery of donor units, could exhibit enhanced TADF performance. Because (i) sufficiently small singlet-triplet states energy gap (ΔEST) and enhanced SOC as well as mixed CT/LE character in T1 state could facilitate reverse intersystem crossing process, and (ii) non-radiative consumption are decreased for S1→S0 transition. Additionally, replacement of As at the connection site between donor and acceptor units folds evidently the geometry, leading to much larger ΔEST and enhanced exponentially SOC between T1 and S0 state due to the great participation of heavy atoms of the frontier molecules orbitals and heavy-atom effect. The pure LE character leads to relative stability and slight non-radiative consumption in T1 state. The luminescent way of DMOC-As-DPS would be transformed to phosphorescence. This work provides updated theoretical perspective for the effect of heavy atoms replacement sites and proposes a design strategy for the utilization of non-metal heavy atoms in efficiency organic lighting emitting diodes.

White Emissions Containing Room Temperature Phosphorescence from Different Excited States of a D-π-A Molecule Depending on the Aggregate States.

Development of pure organic molecular materials with room temperature phosphorescence (RTP) and their applications for white emitters have received significant attentions recently. Herein, a D-π-A molecule (DMACPPY) which can realize white emitting under ambient conditions both in the crystal state and the doped-film state by combining RTP with two fluorescent emissions is reported. The white emission from the crystalline sample of DMACPPY consists fluorescence from S2 (the second excited singlet state) and S1 (the first excited singlet state) along with RTP from T1 (the first excited triplet state), namely, SST-type white light. While, the white emission from the poly methyl methacrylate (PMMA) film doped with DMACPPY contains fluorescences from S2 and S1 , and RTP from T2 (the second excited triplet state) rather than T1 (STS type). DMACPPY cannot exhibit white spectrum within alternative crystalline state since inferior RTP intensity despite similar ternary emissions. The results demonstrate that the emissive properties for excited states of DMACPPY can be tuned by changing the aggregate state from crystalline to dispersion state in PMMA film. This new RTP emitter fulfills the talent for white emitting and achieves dual-mode white emissions, invisibly, expands the application range for pure organic and heavy atom-free RTP materials.

Revealing the reason for the reversal of properties from fullerene to nonfullerene.

The existence of an inflection point between fullerene and nonfullerene molecules was demonstrated using bowl-nonfullerene models, which were proposed to explore the key points relating to the different properties. This study explains the differences in the stacking configurations of the inflection points and reveals the reason for the inversion of properties, which is caused by small structural differences.

Theoretical mechanistic study of 4CzIPN/Ni0-metallaphotoredox catalyzed enantioselective desymmetrization of cyclic meso-anhydrides.

Visible-light-induced inexpensive photocatalyst and transition metal dual catalytic cross-coupling has attracted much attention for efficiently constructing various chemical bonds. The 4CzIPN/Ni0-metallaphotoredox catalyzed enantioselective desymmetrization of cyclic meso-anhydrides with benzyl trifluoroborates has been systematically investigated using density functional theory (DFT) calculations. A radical mechanism merging reductive quenching (PC-*PC-PC--PC) and nickel catalytic cycles (Ni0-NiII-NiIII-NiI-Ni0) is favourable. It consists of seven major processes: single-electron reduction of *PC by benzyl trifluoroborates to generate benzyl radical, ligand exchange, oxidative addition, radical addition, reductive elimination, reduction of NiI by PC- complex via single-electron transfer (SET) process to obtain ground-state PC, and the ion exchange to afford the desired product enantio-enriched keto-acids and regenerate Ni0 catalyst. The oxidative addition is not only the enantio-determining step but also the rate-determining step of the catalytic cycle. In addition, we tried to disclose the origin of high enantioselectivity from both the steric and electronic effects and explain the origin of diastereoselectivity based on the proposed mechanism. Meanwhile, the difference of catalytic activity between Ni0 and NiII as the initial catalysts is caused by the different activation energy barriers based on their respective favourable reaction pathways. This study will hopefully benefit the future understanding of such photoredox-mediated dual catalyzed asymmetric synthesis.

Charge Transfer Mechanisms Regulated by the Third Component in Ternary Organic Solar Cells.

For ternary organic solar cells (T-OSCs), introducing the third component (D2) can significantly enhance the efficiency of cell while still maintaining easy fabrication. However, it brings difficulty in physical understanding of the fundamental mechanism because of the more complicated photophysical processes in T-OSCs. Accordingly, how the guest donor D2 regulates the charge transfer mechanism was explored in theory using three T-OSCs containing two donors and an acceptor. The results point out that larger differences in molecular weight and/or backbone between D2 and the host donor D1 cause different charge transfer mechanisms, which hardly provide a coexisting charge transfer path. Besides, strong absorption capacity of D2 with a high oscillator strength would produce favorable regulation of the charge transfer mechanism. Therefore, this work clarifies the influence of D2 on the charge transfer mechanism in T-OSCs, which suggests that the method of improving the power conversion efficiency cannot be generalized but rather must be tailored to specific conditions.

Protein Kinase D-Dependent Downregulation of Immediate Early Genes through Class IIA Histone Deacetylases in Acute Lymphoblastic Leukemia.

Acute lymphoblastic leukemia (ALL) is a leading cause of cancer-related death in children and adolescents, and cure rates for relapsed/refractory ALL remain dismal, highlighting the need for novel targeted therapies. To identify genome-wide metabolic-stress regulated genes, we used RNA-sequencing in ALL cells treated with AICAR, an AMPK activator. RNA-sequencing identified the immediate early genes (IEGs) as a subset of genes downregulated by AICAR. We show that AICAR-induced IEGs downregulation was blocked by an adenosine uptake inhibitor indicating AICAR was responsible for IEGs reprogramming. Using pharmacologic and genetic models we established this mechanism was AMPK-independent. Further investigations using kinase assays, PKD/PKC inhibitors and rescue experiments, demonstrated that AICAR directly inhibited PKD kinase activity and identified PKD as responsible for IEGs downregulation. Mechanistically, PKD inhibition suppressed phosphorylation and nuclear export of class IIa HDACs, which lowered histone H3 acetylation and decreased NFκB(p65) recruitment to IEGs promoters. Finally, PKD inhibition induced apoptosis via DUSP1/DUSP6 downregulation eliciting a DNA damage response. More importantly, ALL patient cells exhibited the same PKD-HDACs-IEGs-mediated mechanism. As proof of principle of the therapeutic potential of targeting PKD, we established the in vivo relevance of our findings using an NSG ALL mouse model. In conclusion, we identified a previously unreported PKD-dependent survival mechanism in response to AICAR-induced cellular stress in ALL through regulation of DUSPs and IEGs' expression. IMPLICATIONS: PKD mediates early transcriptional responses in ALL cells as an adaptive survival mechanism to overcome cellular stress.

The mechanism of the selective binding ability between opiate metabolites and acyclic cucurbit[4]uril: an MD/DFT study.

Subtle changes in molecular structure often lead to significant differences in host-guest interactions, which result in different host-guest recognition capabilities and dynamics behaviours in complex formation. Herein, we reveal the influence of the guest substituents on host-guest molecular recognition by molecular dynamics (MD) simulation and density functional theory (DFT) approaches. The results suggest that the binding energy barrier of acyclic cucurbit[4]uril (ACB[4]) with opiate metabolites gradually decreases. The methyl group in morphine (MOR) and morphine-3-glucuronide (M3G) strengthens the hydrophobicity of the guest, while depressing the energy loss of the desolvation of polar groups (e.g. hydroxyl) inside the ACB[4] cavity. However, in M3G, the 3-glucuronide group located outside the ACB[4] host cavity effectively alleviates the unfavourable desolvation effect of the hydroxyl and increases the binding constant by two orders of magnitude (compared with normorphine (NMOR)). Our findings stressed the essentiality of the binding mode and intermolecular noncovalent interactions in the host-guest selective binding ability.

A theoretical mechanistic study of IrIII/CuI-metallaphotoredox catalyzed asymmetric radical decarboxylative cyanation.

Visible-light-induced asymmetric metallaphotoredox catalysis has become a powerful strategy in synthetic organic chemistry. IrIII/CuI dual asymmetric catalysis has been developed to achieve enantioselective decarboxylative cyanation. However, detailed mechanisms, such as catalytic cycles for dual catalysts and the role of a chiral ligand, remain obscure in these reactions. In this study, the catalytic cycle of this reaction is systematically investigated by DFT calculations to clarify the quenching mechanism of the photocatalyst and the origin of the excellent enantioselectivity. Interestingly, the radical mechanism merging oxidative quenching (IrIII-*IrIII-IrIV-IrIII) and copper catalytic cycles (CuI-CuII-CuIII-CuI) is favourable. It consists of five major processes: single-electron oxidation of *IrIII by N-hydroxy-phthalimide (NHP) esters followed by decarboxylation to generate benzyl radical, oxidation of CuI by IrIVvia a single-electron transfer (SET) process, cyanide exchange, radical capture by CuII, and C-CN reductive elimination from CuIII. The cyanide exchange is the rate-determining step, whereas the C-CN reductive elimination is the enantio-determining step of the reaction. In addition, the origin of the high enantioselectivity was analyzed from the steric and electronic effects. This study will hopefully benefit the future understanding of such photoredox-mediated dual catalyzed asymmetric synthesis.

Clinical characteristics of 225 patients with COVID-19 in a tertiary Hospital near Wuhan, China.

BACKGROUND: The 2019 coronavirus disease (COVID-19) was first identified in Wuhan, Hubei, China in December 2019, caused by a novel coronavirus (SARS-CoV-2). There is a need to study the clinical features of patients in a hospital near Wuhan. OBJECTIVE: To identify clinical features of patients with COVID-19 in a tertiary hospital near Wuhan. STUDY DESIGN: General information, clinical manifestations, laboratory data, and computed tomography (CT) data were collected for 225 patients diagnosed of COVID-19 admitted between January 20 and February 14, 2020, to the Hanchuan City People's Hospital. RESULTS: The patients included 120 male and 105 females who had no connection to the Wuhan Huanan Seafood Market. Their average age was 50 ±â€¯14 years. The major clinical symptoms were fever (84.44% of patients), cough (56.44% of patients), and dyspnea (4.00% of patients); 3.56%-22.67% of subjects suffered from expectoration, fatigue, chills, headache, chest pain, and pharyngalgia. Hypertension was present in 20.89% of patients. The counts of white blood cells (WBCs) and lymphocytes were normal or decreased in 86.67% and 99.11% of patients. CRP was increased in 86.22% of patients, PCT in 10.67%, and ESR in 90.22%. CT showed that 86.22% of patients had multiple patchy glassy shadows in both lungs, particularly in the peripheral area. Thirty-seven (16.44%) patients were diagnosed with severe COVID-19. Methylprednisolone was administered in 44.44% of cases. The mortality among the patients was 0.89%. CONCLUSIONS: Clinical characteristics of COVID-19 patients in the tertiary hospital near Wuhan are very similar to those found in Wuhan, but the lower mortality.

Design of single-porphyrin donors toward high open-circuit voltage for organic solar cells via an energy level gradient-distribution screening strategy of fragments: a theoretical study.

Open-circuit voltage (VOC) is a key factor for improving the power conversion efficiency (PCE) of bulk heterojunction (BHJ) organic solar cells (OSCs). At present, increasing attention has been devoted towards modifying π bridges in single-porphyrin small molecule donors with an A-π-D-π-A configuration to reduce the highest occupied molecular orbital (HOMO) levels and improve the VOC of devices. However, how to screen the π bridges is a key issue. In this work, nine π bridges were screened by the HOMO level gradient-distribution strategy of fragments (electron-donating donor (D), π bridges, and electron-withdrawing acceptor (A)), where fragments meeting the requirements were combined into five novel small molecule donors. Meanwhile, in order to test whether the strategy is beneficial to increasing VOC, [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) was selected as the acceptor material. The energy levels of all molecules were compared and the photoelectric properties (i.e., energy gap, energy driving force, reorganization energy, intermolecular charge transfer rate, charge recombination rate, and VOC) of the five small molecules were studied. The results showed that the HOMO levels of porphyrin donors could be significantly lowered via this strategy, and VOC was raised without losing the short-circuit current (JSC) and fill factor (FF) of the devices. Meanwhile, the designed five small molecules could be used as donor candidates to improve the performance of OSCs.

Star-Shaped Non-Fullerene Small Acceptors for Organic Solar Cells.

Over the past decade, organic solar cells (OSCs) have received considerable attention from the scientific community and are considered one of the most important sources of low-cost electricity production. Recently, OSC-based on star-shaped small-molecule (SM) non-fullerene acceptors (NFAs) have developed rapidly, and the highest power conversion efficiency (PCE) has exceeded 10 %. The star-shaped SM NFAs not only have three-dimensional charge-transport characteristics similar to fullerenes but also have a strong light absorption capacities and easily tunable energy levels. They are potential candidates as outstanding acceptor materials. In this Review, research progress in of star-shaped SM NFAs OSCs is reviewed specifically. Moreover, the influence of molecular structure, central unit, and peripheral linking group on OSC performance has been evaluated systematically. This Review could stimulate inspiration for designing high-performance OSC acceptor materials in the future.

Construction of Various Supramolecular Assemblies from Rod-Coil Molecules Containing Biphenyl and Anthracene Groups Driven by Donor-Acceptor Interactions.

Rod-coil amphiphilic functional molecules, comprising a rigid aromatic building block and hydrophilic oligoether dendrons as the coil segments, were synthesized. These compounds exhibit a powerful self-organizing ability to form supramolecular nanoparticles and long nanofibers in tetrahydrofuran/water solution, by controlling the intermolecular interaction of the rigid blocks. These molecules are able to form supramolecular polymers and, subsequently, to form sheetlike nanoaggregates, through charge-transfer interactions by the addition of a guest molecule, tetracyanoquinodimethane. Notably, upon addition of water-soluble 2,4,6-trinitrophenol, the self-assembly of these molecules exhibits the antagonistic effect owing to donor-acceptor and hydrophobic-hydrophilic interactions among the molecules. The experimental results reveal that various morphologies of rod-coil molecular assemblies can be obtained by tuning the molecular interaction and the hydrophilicity of guest electron-acceptor molecules. Interestingly, the cross-coupling reaction between phenylboronic acid and chlorobenzene occurs within the charge complexes of these molecular aggregates. This occurs in the nanoenvironment that affords an extremely concentrated reaction zone and reduces the activation energy barrier required for the cross-coupling reaction.

From blue to full color - theoretical design and characterization of a series of Ir(iii) complexes containing azoline ligand with potential application in OLEDs.

Two reported Ir(iii) complexes 1a and 1b containing oxazoline and imidazoline in ancillary ligand, respectively, were investigated by DFT/TD-DFT method. In order to obtain full-color display materials, we designed a group of Ir(iii) complexes 2a-3d based on 1a, which exhibits higher quantum efficiency in phosphorescence, by introducing electron-donating/electron-withdrawing moieties to different positions of the ancillary ligand to adjust emission color. In addition to calculating the radiation rate and analyzing its determining factors, we also estimated nonradiative ability by evaluating the spin-orbit coupling matrix element between the ground state (S0) and the lowest triplet state (T1) as well as the reorganization energy from T1 to S0 to estimate quantum efficiency more accurately. In particular, an in-depth analysis on the contribution of each vibration mode to reorganization energy helped us to identify the effect of substituents on the nonradiative process. Besides, charge injection/transfer properties and energy relation of the states related to exciton quenching via the triplet metal-centered state were also examined, which provide an estimation on the OLED performance of our designed complexes. Overall, we expect 2b and 3c to be more efficient blue-emitting emitters than 1a and 3a and 3b to be efficient green and red emitters, respectively.

Theoretical characterization on photoelectric properties of benzothiadiazole- and fluorene-based small molecule acceptor materials for the organic photovoltaics.

The upper efficiency of heterojunction organic photovoltaics depends on the increased open-circuit voltage (V oc) and short-circuit current (J sc). So, a higher lowest unoccupied molecular orbital (LUMO) level is necessary for organic acceptor material to possess higher V oc and more photons absorbsorption in the solar spectrum is needed for larger J sc. In this article, we theoretically designed some small molecule acceptors (2∼5) based on fluorene (F), benzothiadiazole, and cyano group (CN) referring to the reported acceptor material 2-[{7-(9,9-di-n-propyl-9H-fluoren-2-yl)benzo[c][1,2,5]thiadiazol-4-yl}methylene]malononitrile (1), the crucial parameters affecting photoelectrical properties of compounds 2∼5 were evaluated by the density functional theory (DFT) and time dependent density functional theory (TDDFT) methods. The results reveal that compared with 1, 3 and 4 could have the better complementary absorption spectra with P3HT, the increased LUMO level, the improved V oc, and the decreased electronic organization energy (λ e). From the simulation of transition density matrix, it is very clear that the excitons of molecules 3 and 4 are easier to separate in the material surface. Therefore, 3 and 4 may become potential acceptor candidates for organic photovoltaic cells. In addition, with the increased number of CN, the optoelectronic properties of the molecules show a regular change, mainly improve the LUMO level, energy gap, V oc, and absorption intensity. In summary, reasonably adjusting CN can effectively improve the photovoltaic properties of small molecule acceptors. Graphical Abstract Structure-property relationship of small molecule acceptors could be rationally evaluated in the article. The changes of conjugate length and CN are important strategies to alter the photovoltaic properties of small molecule acceptors. Therefore, taking the K12/1 as a reference, we have theoretically designed a series of small molecule acceptors (2-4). The calculated results by means of DFT and TDDFT manifest that molecules 3 and 4 have the better complementary absorption spectra with P3HT, the increased LUMO level, the improved V oc, the decreased electronic organization energy and the easier separation in the material surface than 1. In summary, reasonably increasing conjugate length and decreasing CN can effectively improve the PCE, which will provide a theoretical guideline for the design and synthesis of new small molecule acceptors.